Solids CaCO3 and CaO and gaseous CO2 are placed in a vessel and allowed to reach equilibrium
CaO(s)+CO2(g)⇌CaCO3(s) ΔH =−180 kJ mol−1
The quantity of CaO in the vessel could be increased by:
Removing some of CO2
Since Kp=1/PCO2, adding CaCO3(s) does not affect equilibrium. Since reaction is exothermic, lowering temperature will shift the reaction to right side. Hence, the quantity of CaO (s) will be lowered. Removing CO2(g) will favor equilibrium to left side. Hence, the quantity of CaO (s) will be increased. Reducing volume will increase pressure. To maintain Kp or PCO2 to a constant value, the equilibrium will shift to right side.